ASTM A320 L7 — Chemical Composition & Mechanical Properties
ASTM A320 L7 is a bolting & nut grades grade for stud bolts / bolting (UNS G41400, EN / W.Nr ≈ 1.7225). It is also known as AISI 4140. This sheet summarises its chemical composition limits, minimum mechanical properties, heat treatment and typical service. Teshi Group manufactures stud bolts and nuts in this grade.
ASTM A320 L7 at a glance
| Specification | ASTM A320 L7 |
|---|---|
| Material family | Bolting & nut grades |
| Product form | Stud bolts / bolting |
| UNS number | G41400 |
| EN / W.Nr equivalent | ≈ 1.7225 |
| Also known as | AISI 4140 |
| Document | TG-MG-039 · Rev. 1 · October 2026 |
Typical service
Low-temperature flange bolting to -101 °C (dia ≤ M65 / 2½ in.)
Heat treatment
Quenched & tempered, 593 °C min temper; Charpy V 27 J avg / 20 J min at -101 °C
Chemical composition of ASTM A320 L7 (weight %)
Single values are maximums unless shown as a range or “min”.
Mechanical properties
| Tensile strength, min | 860 MPa |
|---|---|
| Yield strength, min | 725 MPa |
| Elongation, min | 16 % |
| Hardness | 321 HBW (35 HRC) |
About bolting & nut grades
Flange bolting is specified as a stud-bolt grade plus a nut grade. ASTM A193 covers high-temperature bolting (B7, B7M, B16, B8, B8M), A320 covers low-temperature bolting (L7, L7M, L43, B8 classes), A453 covers high-strength austenitic bolting (Grade 660), and A194 covers the nuts (2H, 2HM, 4, 7, 8, 8M).
Reference information compiled from the published standard for convenience. It does not replace the current edition of the governing standard, which takes precedence. Verify critical dimensions and properties before design, purchase or fabrication. Teshi Engineers & Sales Promoters (P) Ltd accepts no liability for errors or omissions.
International equivalents of ASTM A320 L7
All equivalents| Standard system | Nearest equivalent grade |
|---|---|
| USA — ASTM / ASME | ASTM A320 L7 · ASME SA-320 L7 |
| USA — UNS | G41400 |
| Europe — EN designation | 42CrMo4 |
| Europe — W.Nr | 1.7225 |
| Japan — JIS | SCM440 / SNB7 (JIS G4107) |
| China — GB / NB | 42CrMo (GB/T 3077) |
| China — old GB designation | 42CrMo |
| India — IS | 42Cr4Mo2 (IS 1570) |
| UK — BS (withdrawn) | BS 970 708M40 |
Equivalents are the nearest commonly cited grades. Chemistry, mechanical properties and testing differ between standards — compare them before substituting one for another.
Same alloy in other product forms
| Product form | Specification / grade |
|---|---|
| Stud bolts / bolting | ASTM A193 B7 |
| Stud bolts / bolting | ASTM A193 B7M |
| Stud bolts / bolting | ASTM A320 L7M |
| Heavy hex nuts | ASTM A194 Grade 7 |
FAQ
ASTM A320 L7: common questions
What is the minimum yield strength of ASTM A320 L7?
725 MPa, with a minimum tensile strength of 860 MPa.
What is the carbon content of ASTM A320 L7?
0.38–0.48 %.
What is the UNS number and EN equivalent of ASTM A320 L7?
UNS G41400; the nearest European designation is W.Nr ≈ 1.7225. Equivalents are close but not identical — check the specification if substituting.
How is ASTM A320 L7 heat treated?
Quenched & tempered, 593 °C min temper; Charpy V 27 J avg / 20 J min at -101 °C.
What is the Chinese (GB) equivalent of ASTM A320 L7?
The nearest Chinese equivalent is 42CrMo (GB/T 3077), formerly 42CrMo. Equivalents are close but not identical — compare chemistry and properties before substituting.
What is the JIS equivalent of ASTM A320 L7?
The nearest Japanese (JIS) equivalent is SCM440 / SNB7 (JIS G4107).
Does Teshi Group supply ASTM A320 L7?
Teshi Group manufactures stud bolts and nuts in this grade. Send your size, rating and quantity to info@teshigroup.com for a quotation with EN 10204 3.1 certificates.
Related products, data sheets and standards
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